1. Field of the Invention
This invention relates to valves, and more particularly, to a flapper type check valve for fluids.
2. Description of the Prior Art
U.S. Pat. No. 173,452 (Donovan) discloses a flapper valve disposed in a tube. The flapper is flat, and it moves toward and away from an elliptical aperture with a flat rim or valve seat. The plane of the rim or valve seat is at an angular orientation with respect to the longitudinal axis of the tube other than perpendicular thereto. The apparatus is referred to as a stench-trap, and it apparently is used to keep sewer gases from escaping from the tube in which it is disposed.
U.S. Pat. No. 364,206 (Baltzley) discloses another type of flapper valve designed to be disposed within a pipe. The flapper valve is disposed within a generally cylindrical or circular frame, but having a longitudinally extending slit or slot between the axial ends so that the frame may be compressed or expanded to fit within any given pipe. The flapper is made of flexible material so that it also may be made to conform to the particular diameter of the frame, and accordingly of the pipe, in which it is disposed.
U.S. Pat. No. 385,292 (Baltzley) discloses a drain tile which includes an integral flapper valve. The flapper pivots on the interior or inside of the drain tile between its up (open) position and its down (closed) position.
U.S. Pat. No. 441,751 (Crowner) discloses a flapper valve disposed within a joint of a drain pipe. The flapper valve is planar in configuration. The flapper and its seat are inserted into the joint and are secured therein.
U.S. Pat. No. 452,750 (Drury) discloses another type of flapper valve used as a sewer trap. The flapper is generally flat or planar. The flapper, and its seat, are inserted at a joint of the pipe. The configuration of the flapper, and its seat, provide a restriction in the pipe, and accordingly flow characteristics through the valve apparatus, and through the pipe, are unimportant.
U.S. Pat. No. 1,000,719 (Cram) discloses another sewer trap flapper valve. The flapper is arcuately formed, and the seat conforms to the arcuate configuration of the flapper.
U.S. Pat. No. 1,103,043 (Grueninger) discloses another type of flapper valve in which the flapper valve element is weighted to prevent fluid flow through the pipe when the valve is closed. The valve is designed to be placed in a down spout and extends out to the side of the down spout. The valve pivots away from its closed position to its open position where it is disposed in its own housing or casing off to the side of the drain pipe. The housing or casing is tapered and intersects a down pipe at an acute angle.
U.S. Pat. No. 2,947,321 (Kovalcik) discloses another type of flapper valve in which the flapper pivots freely from its closed position, which is substantially ninety degrees to the flow of fluid, upwardly to allow fluid to flow. The valve and its tubular body extend into the outer end of a pipe for controlling back flow through the pipe. The apparatus is designed to be used within a catch basin and to prevent water flowing through the pipe into the catch basin from flowing backwardly through the pipe. The flapper is flat and is generally circular to conform to the configuration of its pipe.
U.S. Pat. No. 4,095,615 (Ramsauer) discloses a flapper type check valve disposed within a cylindrical housing and inserted into a pipe as a check valve. The flapper has a curved configuration to generally conform to the interior of its housing when it is in the up or open position.
U.S. Pat. No. 4,396,034 (Cherniak) discloses a flapper type check valve in which the valve itself has a cylindrical cross section and angular edges disposed generally perpendicular to each other such that planes along the edges intersect at substantially ninety degrees. The valve seat includes mating edges. The flapper pivots away from its seat on a pivot axis spaced apart from the flapper and its seat. The curvature of the flapper conforms to the curvature of its housing or valve body.
It will be noted that, in the full open position, flow through all of the flapper type check valves discussed above is impeded by the particular geometry involved. Substantial turbulence results, and there is a substantial pressure drop across each of the valves. For the particular applications discussed in the various patents, such pressure drop is generally not important. There are, however, environments in which a pressure drop across a valve in a relatively low pressure flow is most undesirable.
The apparatus of the present invention has been designed to minimize the pressure drop across the valve and to provide the necessary geometry to maximize the flow through the valve and yet to provide a positive seal when the check valve closes.